Harvesters – Motorized harvester – With condition-responsive operation
Patent
1996-08-30
1998-08-18
Melius, Terry Lee
Harvesters
Motorized harvester
With condition-responsive operation
56DIG15, A01O 3486, A01O 7514, A01O 7528
Patent
active
057944210
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for regulating the ground clearance of a working unit of an agricultural machine and, more particularly, to a device for regulating ground clearance of an agricultural machine including a hydraulic control element for adjusting the ground clearance and a control device for generating a control signal for controlling the control element in accordance with sensor signals from sensors including a position sensor which determines the position of the working unit relative to the agricultural machine and a ground clearance sensor which measures the ground clearance of the working unit.
A hydraulic raising device for a combine is already known from DE-PS 15 82 161, wherein the position of the working unit relative to the combine and the pressures occurring in the hydraulic lift device are determined by measuring techniques. These two measuring signals are combined by means of a summing control and an adjustment output signal is generated, taking into consideration the deviation from a defined set value. Since an adjustment of the position of the working unit--in this case a mowing platform, which is intended for cutting grain at a predetermined stubble height above the ground--does not necessarily lead to maintaining a satisfactory constant stubble height, this device is in need of improvement.
Furthermore, it is known from DE-OS 32 40 791 to also measure the ground clearance of a draw-in member by means of a mechanical sensor member in addition to measuring the contact pressure of a draw-in member of a harvester. However, in this known device both values are separately set and also evaluated, which can lead to inaccuracies in working, for example in case of great uneveness of the ground or at great working speeds.
A mixed value setting in connection with lifting units of agricultural machines is furthermore known from EP-PS 0 070 354 wherein, although a combined evaluation of these different measured values is performed, this control is used for optimized force transfer with plowing machines, wherein the ground clearance has no value.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved device for regulating ground clearance of a working unit of an agricultural machine, which does not have the above-described disadvantages.
According to the invention the device for regulating ground clearance of a working unit of an agricultural machine includes a pressurizable control element in the agricultural machine for setting the ground clearance of the working unit from ground over which the agricultural machine moves; a position sensor which detects a position of the working unit relative to the machine and which generates a working unit position signal characteristic of the position of the working unit; a pressure sensor which measures a pressure occurring in the control element and which generates a control element pressure signal characteristic of the pressure in the control element; a ground clearance sensor which measures a ground clearance of the working unit from the ground in a contactless manner and issues a corresponding ground clearance sensor output signal; and a control device for operating the control element to set the ground clearance of the working unit according to the ground clearance sensor output signal alone as ground clearance control signal in a first range closest to the ground, according to the working unit position signal alone as the ground clearance control signal in a second range furthest from the ground and according to a combined signal equal to a mixture of the ground clearance sensor output signal and the working unit position signal in a third transitional range between the first and second ranges. The combined signal is substantially equal to the ground clearance sensor output signal at a position in the third transitional range closest to the first range and the combined signal contains an increasing proportion of the working unit position signal at positions increasingly close to t
REFERENCES:
patent: 4942724 (1990-07-01), Diekhans et al.
patent: 5463854 (1995-11-01), Chmielewski, Jr. et al.
patent: 5473870 (1995-12-01), Panoushek et al.
Melius Terry Lee
Robert & Bosch GmbH
Striker Michael J.
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